Electric meter



Nov. 3. ,1925.

PH. T. WORRALL ELECTRIC METER Filed' Feb 2. 1925 Il -f wumtoz NKY TWINSEND WORRU. 533512, his abme/110g murmur m In f L* Patented Nov. 3, 1925.

UNITED STATES PATENT oFFlcE.

HENRY TOWNSENI) WORRALL, OF CHELMSFORD, ENGLAND, ASSIGNOR .'LO RADIO COR- PORATION OF AMERICA, A CORPORATION OF DELAXVAR-E.

ELECTRIC METER.

Application filed February 2, 1923. Serial No. 616,472).

To all whom it may concern.'

Be it known that I, HENRY TowNsEND lVoRRALL, a subject of Great Britain, and a resident of 202 Springfield Road, Chelms* ford, Essex, have invented certain new and useful Improvements in Electric Meters, of which the following' is a specification, accompanied by drawings.

This invention relates to aninieters and voltmeters of the moving iron type.

According to this invention a meter of this type is so constructed that the moving iron swings in an annular air chamber so that the resistance of the air to the movement of the iron in either direction damps the oscillations of the iron and therefore an external air vane or other damping arrangement is unnecessary. Preferably the inner wall of the chamber consists of part of the frame, while the outer wall consists of a brass tube which can be slipped over the back or lower plate, while the moving iron is in the form of a rectangle extending` from close to the front plate to close to the baci; plate and of width just less than the distance between the interior part of the :iframe and the brass tube.- The rectangular moving' iron plate is preferably -flanged on all four sides to increase the damping effect. The fixed iron is conveniently formed of a tapered strip which can be sprungl on to the outside of the brass tube and easily adjusted to any desired position for calibration. The back or lower portion of the frame with the brass tube in position can be mounted within the solenoid bobbin and secured by the front or top plate of the frame to the flange of the solenoid bobbin.

This invention is illustrated by way of example by the accompanying drawing, Figure 'l of which is a side viewy of the complete apparatus, Figure 2 a part plan, Figure 3 a vertical section and Figure l a horizontal section on the line 4-4 of Figure 3.

A is the bobbin of the meter into which the movement is inserted as seen in Figure 1. The top plate B has formed upon it a portion C which extends downward to the bottom plate D. E is a brass tube which butts against the plate B and is secured in position by screws e in the bottom plate, thus forming a cylindrical chamber. The fixed iron consists of a tapered strip which is rolled into cylindrical form and is sprung upon the outside of the tube E. A spindle G is carried in bearings g, one of which ist mounted in the bottom plate while the other is mounted in a cross bar H connected by screws 7i to the top plate B. This spindle carries a pointer I and has secured to it the inner end of a spiral controlling' spring il, the outer end of which is anchored to a plate l. Secured to the spindle Gr by two nuts Z is a bent arm L formed of thin brass and carrying the moving iron M. This is of rectangular form extendingfrom close to the front plate to close to the back plate and of a width just less than the distance between the portion C and the tube E. The plate is flanged on all four sides so that its movements are damped by the air which is virtually imprisoned between it, the portion C and the tube E and it is therefore unnecessary to employ any additional damping de-A vice as is usual.

Having described my invention what I claim is:

An electric meter comprising' an annular coil, a cylinder mounted inside of said coil, a movable iron member, a spindle carrying an indicatinpy needle rotatably mounted coaxially of said coil, an arm fastened to said spindle and located in a plane perpendicular to the axis of said spindle, said arm having;` an offset portion in the form of an arc con centric wtih the axis of the spindle, said iron member being mounted on the free end of said arm with one edge close to the inner wall of said cylinder and means forming a chamber in which said iron moves throughout its travel to form a dashpot.

HENRY TOVNSEN'D VVORRALL. 

